I\'m using Prism and its working well for CSS:
p { color: red }
but
I actually ran into same issue where i placed prism js and prism css on html page but couldn't get the highlighting. Not sure if it will be the issue with others but for me it was some global css that was set as color black for all "code","pre" tags. After i removed that color from there prism highlighting started showing. If it still doesn't work than you can follow this article Code syntax higlighter using Prism js. I couldn't see much difference but i was having issue when i placed prism js below the code i wanted to highlight. When i moved that to top it started working. If anyone have issue they can try this.